Pharmacodynamics of Ultrasound Guided Popliteal Catheter Infusion after Foot and Ankle Surgery

March 17, 2010

Institutional Review Board, Hospital for Special Surgery

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Principal Investigator

Daniel B. Maalouf, MD, MPH

Co-Investigators

Gregory A. Liguori, MD
Anna Maria Bombardieri, MD
Kethy M. Jules-Elysee, MD
Richard L. Kahn, MD
Andrew C. Lee, MD
Jodie Curren, RN
Barbara Wukovits, RN
James Bae
Valeria Buschiazzo

Summary

Continuous peripheral nerve blockade involves the percutaneous insertion of a catheter directly adjacent to a peripheral nerve. The catheter is then infused with local anesthetic, resulting in potent, site-specific analgesia that lasts well beyond the normal duration of a single-injection nerve block. Ideally Regional Anesthesia provides profound analgesia without complete sensory and motor block. However, a transient insensate limb is a well-recognized effect of perineural local anesthetic infusion and may result in accidental injury.
The aim of the study is to evaluate the effects of varying local anesthetic concentration and volume on inpatients with continuous popliteal sciatic nerve blocks in order to find the optimal local anesthetic concentration and volume that reduces the incidence of insensate limbs and yet maintains effective analgesia.
We propose to compare the incidence of insensate extremity in 2 groups of patients receiving the same LA at the same total dose (16 mg) but at different concentration and infusion rate (0.2% at 8 ml/h vs 0.4% at 4 ml/h). We hypothesize that the incidence of insensate extremity is lower in the group receiving ropivacaine 0.4%  at a basal infusion rate of 4 ml/h.
We will enroll 70 patients (35 per group). The enrollment period will be approximately 1 year. The patients will be enrolled din the study for the duration of the surgery and until discharge or the end of the popliteal catheter infusion, whatever occurs first.

Inclusion/Exclusion Criteria

Inclusion criteria:

• Patients ASA Physical Status I-III, age 18-80, undergoing unilateral, foot or ankle surgery, ability to provide an informed consent.

Exclusion criteria:

• Infection at the site of injection, history of narcotic dependence, current chronic analgesic therapy defined as daily use for more than 3 months before surgery, coagulopathies, known hepatic or renal insufficiency or disease, significant peripheral neuropathy or neurologic disorder affecting the surgical extremity, allergy to study medications, non-English speaking patients. Non-English speaking patients will be excluded because the study depends on a questionnaire (QoR-40) which has not been developed in other languages. It is difficult to construct a translation such that the questions and answers correspond exactly. Also, it may not be possible to have a translator present with the patient when the patient will be approached 3 times a day in order to evaluate the outcomes. For these reasons, we think that using multiple linguistic versions of the survey would introduce added variability and make interpretation of the results more difficult.
  

Contact Information

Daniel Maalouf,MD
Maaloufd@hss.edu
212.606.8636